By MICHAEL ANDERSON

implicity marks the life of Rosa Parks. As a child in Alabama she shared a dirt-floored bedroom with three other children. For most of her life,
she worked as a seamstress. Throughout her 87 years she has been a dedicated churchwoman; ''God is everything to me,'' she once said. And the act that made her world-famous was uttering a single
syllable -- No'' -- when a bus driver named James F. Blake demanded that she, as a black woman, surrender her seat to a white man in accordance with racist laws of Montgomery, Ala., in 1955. Her explanation
was an uncomplicated declaration of human dignity: ''I just wanted to be free like everybody else. I did not want to be continually humiliated over something I had no control over: the color of my skin.''

Her decision on Dec. 1, 1955, sparked a 13-month boycott that ended Jim Crow in the Montgomery bus system. The protest inspired 42 other local protests against Southern segregation within a year. It was the model for the greatest social revolution in
American history, the civil rights movement, which destroyed de jure segregation in the United States; and it was the event that made Martin Luther King Jr. a national figure. However, ''before King there
was Rosa Parks,'' Nelson Mandela has said. ''She is who inspired us, who taught us to sit down for our rights, to be fearless when facing our oppressors.'' (It was ''a Rosa Parks
moment,'' Mandela commented, when a Chinese student confronted an army tank in Tiananmen Square in 1989.) In the words of Vaclav Havel, Parks, one of the century's moral exemplars, is a ''sustainable
hero.''

''What was it that made a reserved, middle-aged black seamstress finally say enough is enough?'' Douglas Brinkley asks in his biography, the first of Parks. ''And where did she get the physical and moral courage to say it
so loud?'' The simplicity of virtue is no less confounding than the banality of evil, and Brinkley, who teaches history at the University of New Orleans, is unequal to its explication. He is considerably handicapped
by a syrupy prose style that prefers stale expression (''quality time,'' ''empower,'' ''role model'') to vividness. (He also can be careless: sloppy sentence
structure has Bayard Rustin rather than A. Philip Randolph threatening a march on Washington in 1941.) More unfortunate, he substitutes a saccharine piousness for spiritual empathy; the simplicity of Parks's life,
faith and commitment defeat him.

However, the Montgomery bus boycott has been the subject of several memoirs and scholarly works, and Brinkley, a conscientious researcher, does a more than adequate job of retelling the familiar story. He also interviewed Parks, and several other veterans
of the civil rights movement; though he frequently pads the narrative, he also can deliver the telling anecdote. Born on Feb. 4, 1913, in Tuskegee, Ala., Parks received an early education in racial oppression. ''By
the time I was 6, I was old enough to realize that we were not actually free,'' she said, recalling the nocturnal assaults by the Ku Klux Klan that caused her grandfather to sleep in a rocking chair with a
double-barreled shotgun in his lap; the young Rosa slept on the floor beside him.

Brinkley's research also allows him to recount the stranger-than-fiction coincidence so often produced by the workings of history. Parks joined the N.A.A.C.P. in 1943, the year she twice was refused the right to vote -- and the same year she first
encountered the bus driver James F. Blake, ''a vicious bigot,'' Brinkley writes, whose ''favorite sport was making African-Americans pay in front and walk back to board in the rear, then
leaving them with a faceful of exhaust as he gunned the bus away.'' He ejected Parks when she refused to board in the rear; she made it a point never to ride a bus Blake was driving, a resolution broken accidentally
on that fateful evening in 1955.

After the Supreme Court ratified the boycotters' victory on Dec. 17, 1956, a reporter and photographer from Look magazine asked Parks to pose for a picture illustrating the new order of integration. The bus they boarded was driven by James F. Blake.

Michael Anderson is an editor at the Book Review. He is writing a biography of Lorraine Hansberry.